Acoustic Modem - use your mobile radio to log in to your buddy's lap top secure

Acoustic modem, pity the fool that doesn't have one.

I bought mine years ago, off the net and had it delivered UPS next day.

I only used it once at a pay phone to log onto the Internet, just to see if it worked.

It worked. 24,000 bps thats better than a 9600 baud modem.

Now if you combine that with a couple of these....

they have privacy codes. Then, you can log on to your buddy's lap top via modem. If it has a telephone input.

If not then you would need some sort of adapter gizmo I guess.

Here is one on Ebay that has the specs

I think it might need some modification to work with a mobile radio. You know it is made for a telephone handset.

What you could do, is get a set of those radios that have ear plugs as an accessory, then just use the ear plus, splice the wire into a telephone.

I am sure it could be done with a little ingenuity.

What do you think? Will it work?

reply to post by Rocketman7


hahah, nice find, reminiscent of "hackers"

Has this combination of devices been tried OP or are you theorizing it would work? Audio modems require duplex handshaking. FRS/GMRS and other two way radios are simplex devices so I don't understand how this would work.

Also I'm not sure what the relevance of the privacy codes is? A privacy code is just a prefix tone that asks other radios to ignore the transmission if they are configured to do so. It is not encryption so it does not provide any security.

reply to post by Rocketman7


thanks for the heads up...

that things cool...

reply to post by dainoyfb


It works the same way single channel radio can send data. Our military does it all the time, no big deal really. Nice thread OP, S&F.

reply to post by BIGPoJo


Source please? How do you get a duplex based modem to work on a simplex radio system. As someone who has designed electronics their whole life I would really like to know how the layman would go about this.

reply to post by dainoyfb


How do you make a phone call over a radio system? Thats how.

Originally posted by dainoyfb
reply to post by BIGPoJo

 

Source please? How do you get a duplex based modem to work on a simplex radio system. As someone who has designed electronics their whole life I would really like to know how the layman would go about this.

Well thank God we have an expert here for this think tank!

OK, TSHTF, you go into the tallest building you can get to, with a car battery in tow. On the roof you set up your RF Transciever

OK, now its your turn to tell us what to do.

Originally posted by dainoyfb
reply to post by BIGPoJo

 

Source please? How do you get a duplex based modem to work on a simplex radio system. As someone who has designed electronics their whole life I would really like to know how the layman would go about this.

Ok I am not an expert. But if I had 4 mobile radios, and I take one, and I press the button, and I attach that to one end of the coupler, and I take the other radio, and I put that on listen.

Then I do the same with another coupler and two more radios, and I hook them up to two lap tops.

I can maybe get some modem software to work, do you not think?

And if I want secure, then I need to maybe encrypt data transfer with encryption protocols.

And use the privacy codes so that other similar radios in town, won't hear what I am doing.

Let me explain further.

You are going to have to design a complex midpoint circuit that stores incoming and outgoing data and then shares the radios for receive and transmit time (since the radios can only receive or transmit, not both at the same time). You will also have to include a circuit that runs the Push To Talk button so that the modem can control the radio when the modem wants to send data or receive data. This circuit will also have to have a remote control channel so that the radios can synchronize with each other so that one is always recording while the other is transmitting. The audio bandwidth on FRS/GRMS radios are extremely limited to a narrow portion of the audio band so that over mod doesn't occur and every radio design is filtered this way to a different degree so much experimentation will be required to realize the data throughput rate. The filtering may be so significant that another circuit may have to be designed to compress the data in order to get a practical baud rate. Software will also have to be written for both ends of the system since the standard continuous packet stream will now have to be replaced with a proprietary, simplex, timeshared protocol.

I think if you used Windows 95 you wouldn't need that modem.

I think you could use a regular modem and wire it into those radio mics. There's a box you can uncheck for Windows 95 to not wait for a dial tone if memory serves me right.

Then you can connect two computers over those radios.

When the internet gets taken down people will create their own. Just as you are doing. Simple to do.

reply to post by Rocketman7




So what your saying is that the OPs suggestion of just grabbing a couple radios, plugging one into the computer with some kind of mystery adapter and the other into the modem with another mystery adapter is complete snakes oil.

If you are no expert and really had no idea if it would really work, why the heck would you post your original comment?

This is not a "anybody can do it" project and intact no expert would do it either since there are far more practical ways to go about it.

This thread needs to go into the HOAX forum.

Originally posted by dainoyfb
reply to post by dainoyfb

 

So what your saying is that the OPs suggestion of just grabbing a couple radios, plugging one into the computer with some kind of mystery adapter and the other into the modem with another mystery adapter is complete snakes oil.

If you are no expert and really had no idea if it would really work, why the heck would you post your original comment?

This is not a "anybody can do it" project and intact no expert would do it either since there are far more practical ways to go about it.

This thread needs to go into the HOAX forum.

Take a pill and chill my special ops friend.

We are not taking over the government here.
You are off topic.

reply to post by Rocketman7


How am I off topic? I'm correcting the OP who is leading readers astray with inaccurate information. I am an expert on the topic and am providing information directly related to the OP. Unless this is the fiction forum and I didn't realize it.

If someone wants to provide a schematic diagram of a tested, working version of this system including a list of the parts suppliers I would very much appreciate it.

Otherwise this thread needs to go into the HOAX bin. This is like suggesting we can fill our gas tanks with salt water instead of gasoline.

Originally posted by dainoyfb
If someone wants to provide a schematic diagram of a tested, working version of this system including a list of the parts suppliers I would very much appreciate it.

Otherwise this thread needs to go into the HOAX bin. This is like suggesting we can fill our gas tanks with salt water instead of gasoline.

Did you read my reply? I am the OP.

You take two radios. Tape the button down on one and attach to the acoustic coupler.

Take the second radio. On listen, attach to the other end of the acoustic coupler.

Attach to your lap top.

Take a second set as above and communicate the range of the radios.

Have two more radios, one for you and one for your buddy to talk and pick a channel. And to set up communications.

He has one frequency, you have one frequency. While talking to him, tell him what frequency you will be on, he puts that on the listening end of the coupler. he tells you what frequency to turn your listen on to.

So now you are sending, he is receiving. He is sending, you are receiving.

And on another channel, you are talking to each other to ensure that the setup is field tested and operational.

reply to post by Rocketman7


So, let's imagine that the layman has figured out how to dig into the radios and fabricate proper line level adapters and that the radios audio filters will somehow pass the bandwidth that the modem requires then how exactly is the laptops communication software going to respond back to and sync with the modem (which has to happen continuously for the communication protocol to work) if the transmit button on the modem end is taped down. Like I said two way radios are simplex based, meaning that they can only transmit or receive, not both at the same time. A modem needs to exchange data in both directions at the same time in order for the computers on each end to synchronize and understand each other (duplex).

reply to post by Rocketman7


So, now you don't need the modem but you need six radios?

Why not just buy two EnGenius EOC56110p bridges for $100 each and plug them directly into your laptops with a piece of cat5. They are rated for 30 Kilometers, have double encryption and 50mbps bandwidth.

Originally posted by dainoyfb
reply to post by Rocketman7

 

So, let's imagine that the layman has figured out how to dig into the radios and fabricate proper line level adapters and that the radios audio filters will somehow pass the bandwidth that the modem requires then how exactly is the laptops communication software going to respond back to and sync with the modem (which has to happen continuously for the communication protocol to work) if the transmit button on the modem end is taped down. Like I said two way radios are simplex based, meaning that they can only transmit or receive, not both at the same time. A modem needs to exchange data in both directions at the same time in order for the computers on each end to synchronize and understand each other (duplex).

edit on 13-10-2011 by dainoyfb because: I typo'd...again.

Ok, you have 6 radios, two acoustic couplers, 2 lap tops.

Ok, you have two radios on the same channel. You attach one to one coupler, and attach the other to the second coupler that you will give your friend.

On one coupler you have attached it to the send, side of the coupler, or talk end of the coupler, and the other set you have set it on the receive end.

Follow me so far? Thats one channel the one radio has the button taped down and it is sending.

The other radio is on listen, and it is listening.

Now you take two more radios and do the opposite to attach them to the other ends of the two couplers but you put those two radios on a different channel.

Ok? So now on one channel one computer will be sending and the other computer will be listening.

On the second channel, the other computer will be sending and the other listening.

Your couplers are connected to your lap tops.

The software, any software merely arranges the handshake, to begin communications. Once the handshake has been established, the computer sends, and waits for an ack. An acknowledgment that the data was received.

And you have communications established, and the software, any modem software is managing the communications.

If the signal is not strong enough get better radios. If, one set loses power, you will see 'lost carrier'

That means you have to try to reconnect.

You will be talking to your buddy on the other set of radios while watching your computer screen. So that you can say to him, well I can't connect on that frequency. Or, you will say to him, ok, I got a signal, we are connected, you are logged on.

By the way, the EOC5611p I mentioned in my last post work very well. I've used them in several applications, usually to wirelessly connect two or more computers together in order to provide video and audio feeds for remote security and wildlife observation. They act as a mini Internet between computers and can also be used as a long range access point. They come with an internal directional antenna but have a connector so you can switch to an external high gain or omni directional antenna.